Assessment of dry eye disease and retinal nerve fiber layer thickness in chronic smokers

Dry eye disease (DED) and retinal nerve fiber layer (RNFL) changes have been independently associated with smoking, but their relationship in chronic smokers remains unclear. This study investigated the impact of long-term smoking on dry eye indicators and RNFL thickness.

This observational case-control study incorporated 100 eyes from 50 individuals aged 30-60 yearsdivided equally into two groups: group A: non-smokers and group B: chronic smokers (≥1 pack/day for ≥10 years). Comprehensive ophthalmic examination included Ocular Surface Disease Index (OSDI) questionnaire, non-invasive tear film breakup time (NIBUT), tear meniscus height (TMH), lipid layer thickness, and RNFL thickness measurements using Fourier-domain OCT Optovue RTVue.

Smokers demonstrated significantly higher OSDI scores (27.2 ± 16 vs 5.5 ± 3.3, p < 0.001), reduced NIBUT, and thinner lipid layers than non-smokers. RNFL thickness was considerably reduced in smokers in superior temporal (129.1 ± 17.7 vs 136 ± 12.2 μm, p = 0.032), inferior temporal, temporal upper, and nasal upper regions, with lower average thickness (99.1 ± 12.1 vs 105.5 ± 7 μm, p = 0.003). Smoking duration and pack-years positively correlated with OSDI scores (r = 0.74, r = 0.71; p < 0.001) and negatively correlated with temporal upper RNFL thickness (r = -0.29, p < 0.05).

Chronic smoking significantly impacts ocular surface health and RNFL thickness, particularly affecting tear film stability and specific retinal regions. These findings suggest increased risk for both DED and optic nerve degeneration in chronic smokers.